During electron beam inspection or electron beam lithography process of the semiconductor device fabrication, the substrate surface, i.e. wafer surface, are irradiated with electron beam. If electric contact of the substrate or wafer is incomplete during irradiation of the electron beam onto an insulator film on the wafer, a charge-up of electrons occurs wherein electrons are accumulated on the interface between the wafer and the insulator film. The charging causes deflection of the electron beam during the irradiation thereof to deform the resultant pattern in the electron beam lithography process and the charge-up restrains the signal electrons emanating from the wafer surface thereof deform the image of surface in the electron beam inspection process.
There are many ways to prevent charge accumulation on wafer surface under electron irradiation. Control landing energy of the irradiating electrons, U.S. Pat. No. 6,734,429 of Takagi; eject rare gas molecules onto the wafer surface during electron irradiation, U.S. Pat. No. 6,465,795 of Madonado et al.; irradiate laser on the wafer surface simultaneously with electron irradiation, U.S. Pat. No. 6,753,524 of Matsui et al.; and the most common way utilize electric contact pins to conduct excess charge away, U.S. Pat. No. 6,068,964 of Komori. The electric contact pins make physical contact to the conductive layer on wafer backside (by means of mechanical punch through) or conductive path is formed between the pins and the conductive layer (by electrically breakthrough the insulator layer), stable potential can be obtained on the wafer conductive layer.
With a conventional electric contact pin housing design, the dimension of tolerance of the hole to let pin through is very tight. There is very little degree of freedom to let the pin move while the wafer slid in and the chucking force applied. Slide scratches within 20 to 30 micron level were found on the backside of wafer and became a particle source of other manufacturing processes. These slide scratches are believed scratched by the electric contact pin during the chucking and de-chucking process.
Accordingly, what is needed is a system and method to address the above-identified issues. The present invention addresses such a case.